This invention relates to combustion driven gas dynamic lasers. "First Generation" gas dynamic lasers ("GDL's") operated with conditions in the reservoir immediately before the expansion nozzles of 20 atmospheres at some 1200.degree.-1400.degree. K. The gas mixtures of about 90 percent N.sub.2, 10 percent CO.sub.2 and 1 percent H.sub.2 O were commonly obtained by burning CO or C.sub.2 N.sub.2 with oxygen and nitrogen diluents, with some additions of hydrogen or a hydrocarbon to produce water vapour.
To produce high laser power it is desirable to operate at higher temperatures and, for compactness, at higher pressures. Also, since cyanogen and carbon monoxide are expensive and toxic fuels, it would be more convenient to use a hydrocarbon fuel, though this implies that the H.sub.2 O/CO.sub.2 ratio in the lasing gases must be raised from 1:10 to much higher values in the range 0.5:1 to 2:1.
Our computer calculations based on Anderson's method (Published in "Physics and Fluids" vol. 13 number 8, pp. 1983-1989, August 1970; "Time Dependent Analysis of Population Inversion in an Expanding Gas" by J. D. Anderson) predicted that GDL's using hydrocarbon fuels would be feasible, and subsequent experiments have indicated that this is the case.
Mobile vehicle-born GDL's, particularly if they are to be provided on an aircraft, should be as small and light as possible. Even in cases where additional weight can be tolerated, such as ship-born lasers, it is still desirable to keep the installation as compact as possible. It is also desirable that the supply of fuel, oxidant and other necessary inputs to the laser be provided as conveniently as possible in terms of apparatus required, cost of such apparatus, and cost of installation.